BHP Billiton's (LON:BHP) Jansen project in Saskatchewan, Canada which has the potential to become the world's biggest potash mine, could get the chop following the break-up of the Russian cartel.

Uralkali is the world's largest potash producer and on Tuesday announced it's ending the decades-old distribution arrangement with Belarus, which controls roughly 43% of global exports, to go it alone.

Uralkali's CEO Vladislav Baumgertner sees the price falling below $300 a tonne before the end of the year from a Vancouver FOB price for the soil nutrient of around $400 a tonne at the moment.

BHP put off a decision on the Jansen project, on which it has already spent $1.2 billion, due to its self-imposed austerity program to cut back on a pipeline of $80 billion worth of large scale projects amid declining metals and minerals prices.

After expansions such as Olympic Dam and Outer Harbour in Australia were ditched, Jansen was considered to stand the best chance among the mega-projects of receiving the green light from the Melbourne-based company's board now that the moratorium on green-lighting big projects had been lifted.

But today's bombshell which at least one analyst described as having the equivalent impact on the potash market as Saudi Arabia leaving Opec would have, puts Jansen's future in serious doubt.

BHP's leadership has made positive noises about Jansen and the potash market before, but the 8 million tonne a year mine which could cost as much $15 billion to construct is probably a no-go with prices at $300 a tonne.

Many considered the greenfield project as the response of ex-BHP CEO Marius Kloppers to Canada's blocking of the Anglo-Australian giant's hostile takeover bid for Potash Corp of Saskatchewan.

Potashcorp's brash CEO Bill Doyle famously said last year of Jansen that "we’ll believe it when we see it" and that "they [BHP] can’t make the numbers work."

Others have been equally skeptical of the project with Canadian investment bank BMO analysts going so far as to classify Jansen as the "worst" move BHP could make to get into the potash game and that BHP's project would need $600 a tonne price to be viable.

Ironically, one of the reasons Potaschcorp and the provincial and federal government was so opposed to BHP taking over the Saskatchewan company, was because BHP said it had no intention of joining Canpotex, the North American equivalent of the Uralkali and Belaruskali sales organization.